| Ceramics has been found extensive promising application in many fields, such as cutting tool, automotive, aerospace and apparatus because of its superior physical and mechanical properties. But ceramics is considered to be typical hard-to-machine material for its high hardness, high brittleness and low fracture toughness. Especially the contour machining of ceramics is a difficult problem which is hoped to be solved for a long time while unresolved yet. It's one of the key research issues for advanced countries to promote the performance of engine made of ceramics at present. This dissertation explores an ultrasonic grinding (USG) technology named NC-Contour Evolution Creep Feed Ultrasonic Grinding (NC-ECCFUSG) ceramic blade surface that similar to NC profiling flank milling so as to resolve the problem of machining ceramic integral wheel. The major research work includes:(1)The primary USG profile machine tool in our library is retrofitted to promote its performance so as to provide a reliable test-bed for the following experiments. A frequency control system is implied to control an inverter-fed motor and a grinding wheel driving system is designed, so as to obtain steady grinding process, install the grinding wheel accurately and make the rotating speed of the grinding wheel steady and controllable. And the ultrasonic vibration system is improved. Function of each unit and design process is introduced in brief.(2)Modal simulation analysis of the stepped horn, the key component of the USM acoustic system, is carried out. On the one hand, the performance parameters of the stepped horn designed according to the theory are not satisfied with the experiment requirement entirely and on the other hand, special structures of the horn in practice including radius of transitional circular are, matching length, flange and screw hole, etc. may lead to the change of its performance parameters, and which is difficult to be solved with analytical method. This problem is resolved through model analysis for the stepped horn. The influences of the radius of transitional circular arc, matching length and connected parts on the resonant frequency, displacement node and transformation ratio of the horn are studied through modal analysis. The stepped horn is designed based on the modal analysis results. Vibration characteristic test of the horn is carried out using method of measuring vibration system with high frequency scanning laser. The actual measuring result matches the modal analysis result approximately, and the discrepancy is less than 2.1%, which indicates that the modal analysis result is reliable.(3)Basic theoretical research on the creep feed USG technology is carried out. Firstly, feasibility of grinding ceramic in the ductile regime is analyzed, mechanism of USG ceramic in the ductile regime is discussed based on the theory of indentation fracture mechanics, and the critical condition of USG in the ductile regime is deduced. Secondly, the model of static load for the material removing in the process of creep feed USG ceramic is analyzed in theory. The model indicates that the grinding force will be reduced when the ultrasonic vibration is applied and the whole grinding wheel cuts into the ceramic, which is of advantage to NC-CECFUSG ceramic blade surface. The theoretic calculating expressions of the maximum grit depth of cut, the contact length in one rotation of the grinding wheel and the surface scallop height in the process of creep feed USG with small diameter grinding wheel are deduced through analyzing the grinding parameters of single grit in the grinding process.(4)Competitive experiments of creep feed ultrasonic face grinding ceramic using small diameter grinding wheel to study the influences of the grinding parameters on the surface roughness and material removal rate (MRR) in the grinding process with/without ultrasonic vibration are carried out to explore relative grinding parameters for the profile grinding. Difference exists in the process of creep feed grinding with/without ultrasonic vibration using small diameter grinding wheel, and which is explained in theory. Deeper research results indicate that the value of ground surface roughness will decrease obviously and MRR will increase a little when additional feed motion is applied to the workpiece. The grinding result is more close to the common theoretic result when increasing the grinding speed through increase the diameter of the grinding wheel. Finally, orthogonal experiments are carried out to study the influence law and prominence degree of the grinding parameters to the ground surface roughness and MRR.(5)Basic technological experimental research on the USG ceramic blade surface is carried out based on the experimental results of face grinding. The mathematical model of the blade with ruled surface is constructed, the machining error is analyzed, the NC machining program is written, the basic technological experiment is carried out and a set of Al2O3 ceramic integrated blades with ruled surface are machined for the first time.
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